1. Field of the Invention
This invention relates to a ventilated disc unit for a brake system adapted for an automotive vehicle or an industrial vehicle.
2. Discussions of the Related Art
One ventilated disc unit is disclosed in JP Utility Model Kokoku No. H 2-38107 (1990). As for this ventilated disc unit, an inner disc and an outer disc are formed as a flat annular member, respectively, with the inner disc having a sliding surface smaller in area than that of the outer disc. The inner and outer discs are interconnected by a large number of radially extending ribs having bifurcated outer ends. Between the inner and the outer disks, a large number of radially extending ventilation passages are formed between the adjoining ribs.
With this type of conventional ventilated disc unit, a large quantity of fresh air is drawn via inner ends of the ventilation passages during rotation of the disc unit for forced ventilation within the ventilation passages before being discharged via outer ends thereof into the ambient atmosphere. This ventilated disc unit has, however, a drawback that the inside of the bifurcated ribs are cooled insufficiently.
JP Utility Model Kokai Publication No. H 2-21342 discloses a ventilated disc unit in which the bifurcated outer ends are formed discontinuously from the radially extending rib as compared with JP U.M. Kokoku No. H 2-38107.
However, it has turned out that there is still much to be desired as to the cooling of the bifurcated point area, i.e., proximity including the bifurcated point.